diff --git a/src/plugins/debugger/debuggermainwindow.h b/src/plugins/debugger/debuggermainwindow.h
index 7755fdacab7..4cc018d5b4d 100644
--- a/src/plugins/debugger/debuggermainwindow.h
+++ b/src/plugins/debugger/debuggermainwindow.h
@@ -37,6 +37,7 @@
 
 QT_BEGIN_NAMESPACE
 class QComboBox;
+class QToolButton;
 class QStackedWidget;
 QT_END_NAMESPACE